Tube-bending plier

ABSTRACT

A tube-bending plier is described having opposing arcuately grooved registering jaws defining a cylindrical engagement segment sized to accept tubing of a particular outside diameter, expanding to oppositely curving arcuately grooved side-jaw mandrel surfaces where, (i) in a first embodiment, the plier handles extending from the plier couple are configured for significantly increasing the distance between the handles for applying torque (τ) relative to a twisting axis aligned in the plane of and extending between the plier handles pivotally closing plier jaws for bending a tube held perpendicularly extending from the plier jaws, and (ii) in a second embodiment, the closed plier jaws and oppositely curving side-jaw mandrel surfaces define a tube bending plane oriented at an acute angle relative to the plane of the pivoting plier handles for applying torque (τ) for bending a tube held within the plier jaws.

RELATED APPLICATIONS

This application relates to and claims any and all benefits of United States Provisional Patent Application No. 61/032347, filed 28 Feb. 2008 entitled, “TUBE BENDING PLIERS.” Provisional Patent Application No. 61/032347 is incorporated by reference in its entirety into this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to tube bending tools and in particular to a tube-bending plier providing mechanical advantage enabling a mechanic to first bend, shaping a hard metal tube and thereafter to grasp and manipulate the shaped hard metal tube into alignment for connection with a designated port.

2. Description of the Prior Art

Every motor vehicle includes shaped hydraulic liquid tubes composed of steel, stainless steel, copper and other malleable metals and alloys connecting between hydraulic power sources and actuators. Such tubing all to frequently fails because of positional wearing against adjacent mechanical components and/or corrosion, and must be replaced. Tube bending is a craft that must be mastered by profession vehicle mechanics. The alternative is distribution and marketing of pre-shaped tubing components by parts manufacturers/distributors for a myriad of different vehicles, with consequent questions of availability.

Hand tools designed for bending tubes without crimping, deforming or kinking the tube walls are well known. They come in three basic embodiments.

The first embodiment is a cast or forged integral body typically presenting a curved bending surface with a capture structure at one end for assuring alignment of a captured tube with the bending surface and a lever arm or coupling for accepting a lever perpendicularly extending from the capture structure. With this bending tool, the tube is introduced into and constrained with the capture structure, then, using the lever arm, the tool is simply rotated on the bending surface bending the constrained tubing. [See U.S. Pat. No. 780,756, Lakin; U.S. Pat. No. 2,280,121 White; & U.S. Pat. No. 5,816,095 Nordell et al.]

The second bending tool embodiment includes a curved bending mandrel mechanically translated between extending yoke arms of an anvil structure bending a tube spanning between the anvil yoke arms. Both the bending mandrel and anvil yoke arms present semi-circular or arcuately grooved surfaces for engaging the tube wall to preclude flattening or kinking as it is bent [See U.S. Pat. No. 5,105,646 Koskinen; and the Lisle 44000 Tubing Bender available from Lisle Corporation Clarinda, Iowa (http://www.lislecorp.com/).]

The third tube bending tool embodiment includes a stationary curved mandrel presenting one or more arcuate peripheral grooves for accepting tubes of particular diameters, a forming member pivotally linked to the mandrel rotatable around the peripheral curve of the bending mandrel, also presenting one or more arcuate forming grooves for accepting tubes of particular diameters, and a mechanical means for securing the tube relative the mandrel and forming member as the forming member is pivotally moved/rotated around the bending mandrel bending the tube. [See U.S. Pat. No. 784,471 Church; U.S. Pat. No. 4,424,699 Peppers; U.S. Pat. No. 7,234,338 Mirtz et al. and the SPX OTC Tubing Bender 6515 available from SPX Corporation Owatonna Minn. (http://www.otctools.com/)]

Pliers are also commonly used by mechanics for bending tubes. The problems typically encountered with tube-bending pliers are not only tube crimping, and deformation, but also scratching or scaring the of tube walls by the plier jaws.

Pliers have even been patented with jaws presenting one or more arcuate registering opposed grooved mandrel surfaces on the jaw sides to alleviated tube crimping and deformation during bending. In particular, U.S. Pat. No. 2,499,160 Pfeiffer describes a plier tube bender having semi-cylindrical jaws at the respective ends of pivotally coupled handles that when closed around a tube, define an open, grooved, curved, bending mandrel extending from the jaw sides around which the extending tube is bent. As illustrated, the bending mandrel of the closed jaws of the Pfeiffer plier curves downward toward the plane of the pivoting plier handles.

A Brake Tubing Forming Plier (Item 49074) available from Easthill Group, Inc. dba Eastwood Company Pottstown, Pa. 19464 (http://www.eastwoodco.com/) have semicircular jaws with oppositely curved integral bending mandrel surfaces curving sideways or perpendicular with respect to the pivoting plane of the plier handles opening and closing the jaws. [See FIGS. 1 & 3.]

The U.S. Manual of Patent Classification includes several subject matter classes and subclasses that include plier type tools for shaping or forming/deforming metals, e.g. class 29, subclass 700+, class 81, subclass 300+ and class 72, subclasses 409.01 and 409.19. Subclass 409.19 of class 72 encompasses plier type tools for working on, or shaping elongated hollow tubes.

SUMMARY OF THE INVENTION

A tube-bending plier is described with opposing arcuately grooved registering jaws defining a cylindrical engagement segment section having a length comparable to that of a selected tube diameter that tangentially expands to oppositely curving, grooved side-jaw, upper and lower mandrel bending surfaces sized to accept the selected tube diameter, that, in a first embodiment, has belled plier handles extending from the pivoting plier couple significantly increasing the distance between the handles for applying torque (τ) relative to a twisting axis in the plane of, extending between the pivoting plier handles for bending a tube held perpendicularly, extending sideways from the plier jaws. A second and third tube bending plier embodiment also have opposing arcuately grooved registering jaws defining a cylindrical engagement segment section of a length comparable to that of a selected tube diameter that tangentially expands to oppositely curving, grooved side-jaw, upper and lower mandrel bending surfaces sized to accept the selected tube diameter, that are oriented for providing a bending plane at an acute angle relative to the plane of the pivoting plier handles for applying torque (τ) for bending the tube held within the plier jaws.

In particular, torque (τ) is the vector cross product of force (F) and a radius (r). Accordingly, increasing a radius at which a force applied to induce rotation about an axis multiplies the force or torque to induce rotation. The described tube-bending plier embodiments simply increase the radius relative to a twisting or bending axis established by the opposing jaws of the plier holding the tube.

A novel aspect of an embodiment tube bending pliers provides oppositely curving side-jaw mandrel bending surfaces curving from each end of the cylindrical engagement section of the closed registering plier jaws giving repairmen greater versatility for grasping, holding, bending, and shaping, and a fixed or mounted tube for connecting its distal end for connection to a distal connection point.

An advantage afforded by the described tube-bending plier is that the cylindrical engagement section provided by the closed plier jaws, allows repairmen to grasp and manipulate and bend, shaped hard metal tubes into alignment for connection with a designated port without scaring or crimping the tube.

DESCRIPTION OF THE PREFERRED AND EXEMPLARY EMBODIMENTS DESCRIPTION OF THE DRAWINGS

FIG. 1 is a comparative schematic diagram showing the jaws of a prior art tube-bending plier.

FIG. 2 is a comparative schematic diagram showing the jaws of a first embodiment of the described tube-bending plier.

FIG. 3 is a perspective view of prior art tube bending plier illustrating the radius for applying torque for bending a tube.

FIG. 4 is a perspective view of a first embodiment of the described tube-bending plier illustrating the increase in radius for applying torque for bending a tube achieved by “belling” the plier handles.

FIG. 5 is a side perspective view of a second embodiment of the described tube-bending plier illustrating the increase in radius for applying torque for bending a tube achieved by orienting the opposing, arcuately grooved, registering jaw and jaw mandrel surfaces of the plier defining a bending plane at an acute angle relative to the plane of the pivoting plier handles closing the plier jaws.

FIG. 6A is a top perspective view of the second embodiment (FIG. 5) of the described tube-bending plier.

FIG. 6B is a side plane view of the second embodiment (FIG. 5) illustrating the angle of the tube bending plane relative to the plane of the pivoting plier handles established by the cylindrical engagement section and the oppositely curving, grooved side-jaw mandrel surfaces of the closed plier jaws.

FIG. 7 a shows a top plane view of a third embodiment of the described tube-bending plier with oppositely curving side-jaw mandrel surfaces extending from each end of the cylindrical engagement section of the closed plier jaws.

FIG. 7 b shows a comparative schematic diagram of the engaging jaws with oppositely curving side-jaw mandrel surfaces curving tangentially extending from each end of the cylindrical engagement section of the closed plier jaws.

FIG. 7 c is a side plane view of the third embodiment of the described tube-bending plier with oppositely curving side-jaw mandrel surfaces tangentially extending from each end of the cylindrical engagement section of the closed plier jaws.

FIGS. 8 a-8 d are diagrams illustrating the versatility of the third embodiment of the described tube bending plier for grasping, bending shaping and holding a tube extending from a fixed position for coupling its distal end to at distal connection point.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIGS. 1 & 3, typical commercially tube bending plier available to car repair mechanics from tools vendors, suitable for bending stiff, steel brake-line tubing have plier jaws with arcuately grooved oppositely curved side-jaw mandrel surfaces, that close tightly around a tube and tend to annularly crimp or cut into the tube surface as the repairman bends the tube around a curved side-jaw mandrel surface of the plier. In particular, the plier jaws must be held tightly closed around the tube, as it is bent, first to apply or resist torque required to initiate the bend, then to resist the torque for conforming the bending tube to the curved mandrel surface relative to a twisting axis determined by the plier jaw engagement surfaces. The plier jaw engagement segment of typical prior art tube-bending pliers for holding the tube, as indicated by the arrows in FIG. 1, are narrow relative to the tube diameter, thus concentrating stress for straining/deforming/bending the tube initially to the narrow annular region of the tube actually engaged by the plier jaws.

In contrast, looking at FIGS. 2, and 7 b the closed jaws of the described tube-bending pliers provide a cylindrical engagement segment, indicated by the arrows in FIG. 2, having a length comparable to the diameter of the held tube that distributes stress along the length of the cylindrical engagement segment for initially straining/deforming/bending the tube.

FIGS. 3 shows a typical prior art tube-bending plier having plier handles that extend more or less straight out from the pivot couple of the plier at sleight angle to provide essentially a constant radius R_(PA) relative to the plier tube twisting axis defined by the closed plier jaws grasping and holding the tube as its bend conforming to the side-jaw mandrel surfaces.

In contrast, as shown in FIG. 4, the handles of the invented tube-bending plier initially extend straight out from the pivot couple of the plier a sleight angle, then bell oppositely, outward defining a radius relative to the plier twisting axis defined by the cylindrical engagement segment of the closed jaws that varies across the width of a grasping hand for orienting the hand for locating a maximum radius R_(MAX) relative to the twisting axis between the base of the thumb and the base of the little finger, i.e. the belled handles orient the grasping hand such that the largest diagonal across a grasping hand is perpendicular relative to the twisting axis of the tube bending plier.

The second embodiment of the invented tube-bending plier illustrated in FIGS. 5 & 6 includes opposing, arcuately grooved, registering jaws providing a cylindrical engagement segment with oppositely curving, grooved, side-jaw mandrel surfaces tangentially extending from one end of the engagement segment that are both oriented to provide a bending plane at an acute angle relative to the plane of the pivoting plier handles such that the torque (τ) that can be applied for bending or resisting bending of tube is determined by the length (R) of the plier measured from the cylindrical tube engagement section of the closed plier jaws and the distal ends of the plier handles.

FIGS. 7 a, 7 b, and 7 c illustrate a third embodiment wherein the oppositely curving, grooved, side-jaw mandrel surfaces tangentially extend from both ends of the cylindrical engagement segment provided by the closed plier jaws that are, again oriented for defining a bending plane at an acute angle relative to the plane of the pivoting plier handles closing the plier jaws.

FIGS. 8 a through 8 d illustrate the added versatility of the third embodiment of the invented tube-bending plier gained by providing oppositely curving, grooved, side-jaw mandrel surfaces tangentially extending from both ends of the cylindrical engagement segment provided by the closed plier jaws. In particular, a fixed tube can be grasped, bent around a front-end, upper or lower mandrel surface, or bent around a rear-end, upper or lower mandrel surface giving a repairman great flexibility in bending shaping, aligning and then fastening a fixed tube, (secured at one end to a port) successively, in segments around intervening structural surfaces for connecting the distal tube end to a distal connection point.

Skilled tool designers and professional mechanics should note and appreciate that providing oppositely curving, grooved, side-jaw mandrel surfaces tangentially extending from both ends of the central cylindrical engagement segment provided by the closed plier jaws similarly increases the versatility of tube-bending pliers having a twisting axis in the plane of, between the pivoting plier handles (FIG. 4) for grasping, bending, shaping, holding and aligning a fixed tube for fastening its distal end to a distal connection point.

Skilled tool designers and professional mechanics should also note and appreciate the cylindrical tube engagement segment provided by the closed jaws of the invented tube-bending plier having a length comparable to that of a particular tube diameter are ideal for grasping, manipulating, holding, removing and replacing shaped tubes connecting between ports in close quarters typically encountered when removing and replacing such tubes in mechanical machines, e.g., motor vehicles.

The invented tube-bending pliers are described in context of three specific preferred embodiments. Skilled tool designers and professional mechanics should understand and realize that many alternatives, modifications and variations, of the described tube-bending pliers are possible for effecting the desired functionality meeting constraints imposed by different mechanical systems, that will perform substantially the same function, in substantially the same way to achieve substantially the same result as the above components described and specified by the Applicants Accordingly, while mechanical components suitable for implementing the invented hydraulic transmission system may not be exactly described herein, they may fall within the spirit and the scope of invention as described and set forth in the appended claims. 

1. In a tube-bending plier having oppositely arcuately grooved registering jaws with oppositely curving, arcuately grooved, side-jaw mandrel bending surfaces sized to accept tubing of a selected outside diameter, an improvement comprising semi-cylindrical engagement segments in the arcuately grooved registering jaws for providing a cylindrical engagement segment for grasping and holding the tube with a length comparable to the selected outside tube diameter, and wherein each curving, arcuately grooved, side-jaw mandrel bending surface sized for the selected tube diameter curves tangentially from an end of each semi-cylindrical engagement segment.
 2. The tube-bending plier of claim 1 wherein plier handles extending from a pivoting couple of the plier for closing and opening the plier jaws are configured for significantly increasing distance between the handles for applying torque (τ) relative to a twisting axis aligned in a plane defined by, and extending between the pivoting plier handles.
 3. The tube-bending plier of claim 1 wherein the opposing, arcuately grooved, registering jaws and arcuately grooved side-jaw mandrel surfaces of the plier are oriented for providing a bending plane at an acute angle relative to a plane defined by the pivoting plier handles opening and closing the plier jaws for increasing torque (τ) for bending the tube held within the jaws of the plier.
 4. The tube-bending plier of claim 1 wherein the curving, arcuately grooved, side-jaw mandrel surfaces sized for the selected tube diameter curve tangentially from each end of each semi-cylindrical engagement segment providing a front-end, upper and lower mandrel bending surfaces and a rear-end upper and lower mandrel bending surfaces.
 5. The tube-bending plier of claim 3 wherein the curving, arcuately grooved, side-jaw mandrel surfaces sized for the selected tube diameter curve tangentially from each end of each semi-cylindrical engagement segment providing a front-end, upper and lower mandrel bending surfaces and a rear-end upper and lower mandrel bending surfaces. 